Share 'How can I learn to write atonal music?'

I want to ask the question that was suggested in another thread because I think it's important. The question is: How should an inexperienced composer who wants to write dissonant and rhythmically complex music learn how to do that?
I've been writing and playing music a long time but I'm basically a beginner at 'classical' composition. I can read score at an intermediate level. I know basic theory…